Method and apparatus for producing oil



Oct. 25, 1932. l. B. WILLIAMS 1,884,459

METHOD AND APPARATUS FOR PRODUCING OIL Filed A Sril 25, 1930 INVENTQR. #14729 63 W/W/ams A TTORN Patented Oct. 25, 1937 PATENT OFFICE IRVING B. WILLIAMS, OF TULSA, OKLAHOMA METHOD AND APPARATUS FOR PRODUCING OIL Application filed April 23,

This invention has to do with a method of increasing the production of oil from oil wells and provides a means for,

(a) Securing a greater economic production of oil from the oil sands,

(b) To conserve the natural gas and gas pressure in the formation for future use in securing longer flowing life to oil wells,

(0) To obtain a higher gravity well,

(d) To prevent the encroachment of Water into the oil sand and production of water from an oil'Well. In (0) above, the A. P. I. gravity of the oil is increased by the use of the flow control device due to the fact that the back pressure imposed causes a substantial absorption and retention of gas and light hydrocarbons such as gasoline, naphtha and l1ke materials, normally released by open flow methods and methods not employing back pressure. I

The invention eliminates the use of expensive compressors and gas lift equipment, and, to a'large measure, oil water treating equipment which, in many cases. makes the production of oil unprofitable. When properly operated, no water will be produced from the well, therefore a tremendous saving can be made not only in eliminating the treating cost of the oil produced, but also in the lift ng cost. The lifting cost of this method is equivalent to that of a naturally flowing well.

The present invention operates with a natural reservoir pressure of the oil sand by use of a very small flow device interposed in the tubing, el minating other equipmrnt such as compressor plants, pumps and expensive auxiliary machinery. The only equipment necessary, as suggested, outside of the flow device, is the ordinary equipment used in flowing wells, such as a casing head, oil well tubing, gas trap and stock tanks.

It is well known in the art of producing oil that an oil well flows naturally for a short time, this period constituting from a few days to a few months, after which it is ut on the pump and the oil thereafter produced at great expense until it is no longer profitable, due to water production drowning out the oil, or from lack of gas and gas pressure to propel the oil from the oil sand into the well.

1930. Serial No. 446,517.

It has been estimated that only about 15 per cent of the oil can be removed by these open flow methods because the gas and gas pressure have been dissipated rapidly during the period of natural open flow.

It is a well known fact that open flow methods of oil production quickly rob the sand near the bottom of the well of light gases and light volatile constituents. The sand is rapidly depleted of gas and gas pressure for a short radius around the bottom of the well. This depletion of gas pressure is accompanied by the sealing up of a large percentage of the sand pore openings by deposition of a heavy residue oil of high viscosity which effectively plugs ofl the gas and oil in the oil sand from coming into the well. This heavy residual oil is produced by evaporation from the crude by the dissipation of the gas and the light volatile constituents of the oil.

Furthermore, because there is a high differential flowing pressure from undisturbed areas back in the oil reservoir or sand to the bottom of the well existent in open flow methods of production, water flows rapidly into the well and traps ofl large areas of oil and very soon drowns out the well. The present method and device for applying back pressure up to a critical point maintains an o l sand reservoir pressure without reducing the amount of oil production per day. At the same time, it prevents the movement of water throughout the sand into the well. Due to this back pressure, the gas and gas pressure are conserved in the oil formation or sand so that there is an increased ultimate production obtained and longer flowing life, up to three to four times as long as that procured by open flow practice. The rate of production decline is checked considerably and in actual practice instances have occurred where this decline has been checked to one tenth of the decline experienced with open flow methods.

The following is a brief dissertation on my bel ef as to whether this back pressure imposed upon the well accomplishes the results obtained, and it is offered not to restrict the invention but in an endeavor to explain the effect which the flow device has upon the oil production of a well. When back pressure is applied at the sand face of an oil well, the static pressure in the sand area immediately surrounding the bottom of the well is raised. The increased static pressure compels a reabsorption and redissolving of natural gas and light volatile fractions back into the oil. This reabsorption of gas lowers the viscosity of the oil and increases its fluidity. The oil then flows more easily through the sand and, even though the differential flow pressure between the oil sand and the bottom of the well has been reduced, the velocity of the lowered viscosity oil is increased up to a predetermined critical point of back pressure applied so that back pressure in excess of this critical point creates a loss of oil production per unit time. I

Reduction of the differential flowing pres-' sure between the oil sand and the bottom of the well by the imposition of back pressure has a very different effect upon the flow of water or water production in the well. Water does not absorb gas except. to a very limited extent. Therefore, the flowing characteristics in the well are relatively unchanged because there is no viscositv change. A small decrease in the differential flowingpressure, therefore, decreases the velocityof P water flow enormously because the friction in the microscopic sand pores is very great and a small amount of back pressure Wlll reduce the production of water greatly and, long before the critical back pressure is reached. the movement of water through the sand will be completely stopped. In other words.

the imposing of a back pressure upon the well.

checks and effectively stops the flow of water from the sand or surrounding formation into the well. I

Gas velocity is also decreased to approach the slower velocity of the oil, hence by-p'assing of the gas through the oil is lessened, which tends to bring out more oil in a given time period. Gas pressure and gas volume are likewise conserved in this way. The gas pressure and oil of a formation are mamtained at all times available-at the face of the sand. The oil is kept ina highly gas charged effervescent state very similar to the con-' dition met with when ai well is first drilled in. This method contemplates the use of a flowing device which is interposed in the tubing at a predetermined position as hereinafter described.

Fig. 1 is a sectional view showing the fiow-' in device positioned in the tubing of an oil Fig. 2 is an enlarged detail of the flowing device. 1

' Fig. 3 is a bottom view of the flow device with the choker and choker holding plate removed.

Referring the drawing, the ground level is shown at 1, the oil sand at 2, with acap rock structure diagrammatically shown at 3. The

numeral 4 designates the casing which is capped at the top by a tubing head 5. lVithin the casing is a tubing 6, at the lower end of which is a dead end nipple 7,'acollar 8, and a perforated length of tubing 9, which is adjacent the oil sand and into'which the oil flows. The fiowingdevlce is designated as a sure gauge 17 is also tapped into the line 15.

A pressure relief line 18, controlled by a valve 19, is connected into the casing above the ground leveL' Between the valve 19 and the casing is a pressure gauge 20.

Referring back to the flowing device designated as 10 and shown in Fig. 2; this device has a body portion 21 internally threaded at both ends to be positioned between two joints of ordinary well tubing. The body portion has a plurality of tapered threaded holes radially bored therein to receive the gas port lugs 22. A metal sleeve housing 23 covers all of the gas ports when in operation and is used-to prevent dbris coming in contact with the small diameter gas'ports 'which extend throughout the center of .the gas port plugs. Lead gaskets 24, fitted under the lower end and on top of the upper end of the'sleeve housing assure a dbris tight fit between the housing and the'fiowingdevice body. This sleeve is firmly held in place by a sleeve retaining ring screw clamp 25. A fine mesh screen 26 covers the gas feeder holes 27, drilled longitudinally of the body 21,'connecting the gas chamber 28 behind the sleeve 23 with the space between the tubing 6 and the casing 4. Thus the gas inthe well is given free access through the gas feeder ducts 27',

through the'ga-s chamber 28 with the ports in the plugs 22. The purpose of the screen 26 covering the inlet of the holes or ducts 27 is to prevent the passage of dbris or deleterious matter into the small gas port openings in the plugs 22. The gas ports inthese plugs, designated by the numeral 29, are jeweled by a' hard, resistant'material which withstands the effect of erosion and corrosion. These jeweled ports 22 vary in diameter below 0.052 inches, are mounted in the plugs 22 and supply a small amount of gas into the tubing 6 from the annular space between the casing 1 and the tubing 6.

As suggested, the purpose of the jewel sur rounding the gas I ports is to reduce thegas through the jeweled gas ports 29 is to supply a deficiency of gas to the oil which has come through the choker 30 and mixer 31, in order to make a correct mixture of gas and oil prior to the ascent of the oil through the upper length of the tubing. The choker 30 consists of a plug screwed into aplate 32, the latter being. threaded into the flow device body.

The mixer 31 is a perforated plate, positioned above the choker which serves to further disperse the oil which is broken up by passing through the constricted opening designated asthe choker. i The introduction of this small gas supply through the gas ports 29 also acts as a gov-- ernor upon the entire flow device mechanism, including the annular spacebetween the easing and tubing, the pressure on the sand, and the pressure on the upper side of the choker; in other words, producing and maintaining an equilibrium or equipoise condition between all phases of the flowing device; and prevents what is termed long heading or intermittent blowouts of the oil produced by building up a momentary high gas pressure in the annular space between the casing 1 and tubing 6, with consequent high back pressure on the sand. This long heading or the creation of relatively long heads of oil produces a violent rush of gas which causes a longheadflow, which produces, immediately thereafter, a lowered back pressure upon the sand below the desired amount which produces intermittent and irregular flow at the surface. In

. other words, without the governing effect of the small supply of gas through the jeweled gas. ports 29, the casing head working pressure will vary between wide limits, thus exerting an excess back pressure on the sand followed by a deficient back pressure and with 21 consequent loss of gas, light hydrocarbons, and oil production. i

The method contemplates the use of a constriction element or choker device 30 in combination with a plurality of gas inlet ports having a definite relation as to area relative the area of the constriction port in the choker. It is essential to maintain a constant ratio between the area of the aperture in the choker through which the oil passes and the combined areas of the gas ports through which deficiency the auxiliary gas is. introduced. This ratio is maintained irrespective of the casing head working pressure and daily oil production for any given lift or position of the flow device in the vertical tubing.

The mixer or spreading plate 31 is set a shortdistance above the outlet of the choker 30 and, as suggested, is used to breakup the oil stream coming through the choker into a number of streams of oil just'prior to the point where the oil meets the deficiency gas supplied through the jeweled gas ports 29. This action secures a correct mixture of the 'oil,'gas, and semi-volatile hydrocarbons prior to flowing of the mixture up through the tubing. The choker is used indifierent sizes, varying by 64ths of an inch in diameter as required to deliver the desired amount of oil that the exposed sand will deliver continuously with the required back pressure exerted on it. It has been found that 64ths of an 'inch difference in the diameter of the choker aperture is the largest tolerance permissible for correct adjustment. Oil wells which vary in the conditions of gas pressure and flow rate will require different choker sizes and gas port sizes toaccomplish or produce in the bottom of the well in'Fig. 1, is generally placed 40 feet or two joints above the bottom of the well hole in order to keep the inlet holes clear of dbris.

The critical back pressure as herein used is reached when the favorable effect of fluidity change and lowered viscosity of the oil by the absorption of gas and gaseous constituents is exactly balanced by the opposite effect of lowered differential flowing pressure. Back pressure applied beyond this point will result in decreased oil production per unit time because the velocity of the flowing oil beyond the critical point decreases almost proportionately as the back pressure applied. In other words, there is a velocity increase of the lowered viscosity oil until the critical back pressure is reached after which there is a velocity decrease almost in direct proportion to the amount of back pressure applied beyond the critical point. The back pressure has been referredto as a pressure which creates certain critical conditions within the' well. These desired critical conditions of back pressure created in any particular well are attained when'the follow ing conditions exist or occur 1. An optimum differential flowing pressure between the oil sand and the bottom of the well is obtained or arrived at when such differential flowing pressure is accompanied new conditions of flow over a period of a few weeks the string may be pulled and any necessary adjustment of the elements of the device made. The flow device may be positioned relative the perforated nipple by interposing two or three joints therebetween, depending on the condition of the hole.

In making an installation in a new field, it is necessary for the first installation, to assume the casing head working pressure from the particular data observed on the well or adjacent wells. If the absolute pressure of the formation can be obtained, the casing I head working pressure could be computed very accurately, but this is seldom possible except on anew well where a shut-in reading of the pressure may be observed shortly after the well is drilled in. A well that has been producing by the open flow method for a long time will not show a shut-in pressure that is reliable or even a very good indication of the formation pressure because a large percentage of the sand pores are sealed and plugged by rapid exhaustion of the light volatile constituents. Therefore, it is necessary to depend upon observed data from the general knowledge of the field. A safe assumption for easing head working pressure, if there are no reliable data at hand is one pound per square inch for every ten feet of depth of the flow device. (Thus, if the depth of the flow device were 3,000 feet, about 300 pounds per square inch casing head working pressure would be a safe assumption for the initial installation!) The following is an example of an actual installation Well data Oil production 200 barrels per day Total depth "4000 feet Casing head working pressure 300 pounds Depth to top of sand "3980 feet Depth of flow device 3600 feet Gravity of oil 38 B.

- gas is figured from the total by the natural gas pressure is increased within the well, tending to lift the oil out of the well, introducing directly a predetermined increment of said pressure into the efliuent column above the point of restriction whereby said pressure increment will oppose the pressure lifting the oil out of the well so that only the differential pressure thus created will be effective in lifting the eflluent oil, resulting in a reduced flow velocity and a conservation of the natural gas pressure.

2. The method of controlling the flow of oil from an oil well in which natural gas and oil are present, which includes the steps of restricting the flow of the effluent oil, whereby the natural gas pressure is increased within the well, tending to lift the oil out of the Well, comminuting said restricted stream, introducing directly a predetermined increment of said ressure into the efiluent column above the point of restriction whereby said pressure increment will oppose the pressure liftin the oil out of the well so that only the differential pressure thus created will be effective in lifting the efiluent oil, resulting in a reduced flow velocity and a conservation of the naturalgas pressure.

3. In an oil well having an eduction tube,

the combination including a cylindrical member having abore adapted to be interposed in said eduction tube, a choke for said bore, and means in direct communication with the natural gas pressure within said well for admitting a predetermined increment of said pressure to said bore at a point above said choke.

4. In an oil well having an eduction tube, the combination including a cylindrical member having a bore adapted to be introduced in said eduction tube, a choke for said bore, means for comminuting the eflluent stream ositioned within said bore above said cho e, a plurality of ducts placing said bore in direct communication with the natural gas pressure within the well, and a plurality of nozzles of predetermined cross seetional' area, adapted to control the pressure of the gas admitted to said bore through said ducts.

In testimony whereof I aflix my signature.

IRVING B. WILLIAMS. 

